pfannkuche



(No Model.)

2 Sheets-Sheet 1. G. PPANNKUOHE. METHOD OF INDIOATING THE STRENGTH OF THE GURRENT IN AN ELECTRIC CIRCUIT.

Patented June 11, 1889.

(No Model.) 2 Sheets-Sheet 2.v

G. PPANNKUOHE. METHOD OF INDIOATING THE STRENGTH OF THE CURRENT IN AN ELECTRIC CIRCUIT.

No. 404,861. Patented June 11, 1889..

e 9 9g es ee e e 1/ l I r z ee ee 9e 99 e 5140c wfoz litmeooeo to be a full, clear,

invention, such as will enable others skilled to provide a simple,

UNITED STATES GUSTAV PFANNKUCIIE, OF 'CLEVELAND, OHIO, ASSIGNOR TO PATENT OFFICE.

THE BRUSH ELECTRIC COMPANY, OF SAME PLACE.

METHOD OF lNDlCATlNG THE STRENGTH OF THE CURRENT IN AN ELECTRIC CIRCUlT.

SPECIFICATION forming part of Letters Patent No. 404,861, dated June 11, 1889. Application filed DecemberlS, 1888. Serial No. 293,712. (No model.)

State of Ohio, have invented certain new and.

usefulImprovements in the Method of Indicating the Strength of the Current in an Electric Circuit; and I do hereby declare the following and exact description of the in the art to which it appertains to make and use the same. My invention relates to an improved method of indicating the strength of the current in an electric circuit, or for indicating the difference of potential existing between two points in an electric circuit, the object'being efficient, and reliable method for'indicating and determining the strength of an electric current, whether it be continuous, alternating, pulsating, or intermitting current.

With this object in view my invention consists in the method of indicating the strengthof' an electric current by converting the current to be measured, or a portion of it, into'a thermo-electric current and utilizing the latter to actuate a suitable indicating apparatus.

-- The invention further consists in certain other features of improvement, as will be-hereinafter described, and pointed out in the claims.

Inv the accompanying'drawings, Figure l'is a diagrammatic view, in side elevation, of one form otapparatus embodying my invention.

- same. Fig.

a similar view in cross-section of the 3 is a vertical section of one of the series of high-resistance'wires employed Fig. 2 is p in an apparatusemployed to measure the difof high-resistance wires;

ference of potential between the points of a circuit, Fig. 4 being a transverse section of the same, showing a plan view of two series and Fig. 5 is 2. dia grammatic view showing the apparatus in the circuit of a dynamo-electric machine. Fig. 6 is an enlarged view of the apparatus.

' H is the base-board of the instrument, and

. is made of wood or other suitable material.

On the base-board are placed the bars a a,

. which are made of any suitable form and dimensions, and composed of German silver or other suitable conducting metal or metals. Between the bars an and a. a are insertedthe alternate joints of the thermo-pile of thermo-spiral B B, the joints being insulated from the bars by thin plates P, of mica or other suitable insulating material. The bars, insulating-plates,\and thermo-spiral are socured together and to the base-board H by means of insulated bolts or screws O. The German-silver bars a are provided at their ends with the terminals 0 C, while the bars a are provided with end terminals C 0 G. represents a galvanometer, which may be of any preferred type or construction, and is provided with an index R, arranged to move forward'and backward over a scale S, the index B being fixed'to a needle T, to which latter is secured a vane E. .The galvanometer is included in the circuit of the thermo-spiral E13 by means of the conductors e e, which connect the helix of the galvanometer with the terminals D D of the thermo-spiral, which latter, as stated, may be of any suitable form or material.

The parts of the apparatus, excepting the galvanometer, are inclosed in the box and completely covered and concealed thereby.

The sides or other portions of the box are provided with perforations b for the purpose of ventilation. The box is furnished with a longitudinal partition U, dividing the interior of the box into two compartments, in one of which are located thebars a a and the joints of the thermo-spiral that connect therewith, while in the other compartmentare located the bars a a I and the joints of the thermo-spiral that are connected with them. The partition serves to prevent the heat of bar a from com-' municating or being transmitted to the bar a. In the operation of the apparatus the current to be measured, or a portion of it, is first converted into a therrno-electric current, the.

thermo-pile standing in the same relation to the main circuit as a converter, the primary coil of the thermo-pile being represented by the heating bar ordevice through which the current to be measured is passed. As is well known, variations of heat. applied to the alternate joints of a thermo-pile produces variations in thecurrent generated or produced by the thermo-pile, so that the variations of current to be measured are indicated by the variations in. the strength of thethermo-electric current. Myimproved apparatus is pref- ICO erably constructed so that when no current is passing through the heating wire or rod the two sets of alternating joints of the pile are of exactly the same temperature, and hence when no current is passing through the device the galvanometer. will always point. to

.zero. Upon the passage of current-through the bar ct, to the terminals of which are connected the ends of the circuit in which the current is to be measured, the bar will commence to heat, and'the heat'will increase as the current to be measured increases in quantity, the temperature of the bar a varying v with the varying quantity of current passing through it, and as the difference of temperature of the bars a a .varies will be indicated by the deflections of thegalvanometer, so that the latter operates to I indicate and serve as a measure of the current passing through the bar a. The bars aa are 7 made of the same material, and are uniform in size andshap'e and in every way, so that- "thermo pile,

the temperature of the alternate joints of the when no currentis passing through theinstrument, will always be the same, regardless of what the temperature in the containing I known-fact that the difference 3 box or room inwhich the apparatus is placed may be. In View of the wellof potential of ather'mo-pile depends for given material "and construction only on the difference of temperature of its alternate joints, it follows that the instruments readings must always be correct, no matter whether the-outside temperature be high or low, and it'is by the Var ing strengths'of the the'rmo-electric current,which. act. upon and are recorded by thegalvanometer, that I, am enabled to measurethe strength of the current in a circuit without employing- 1 moved from one'series to- "tion of the wire; and Fig. 5 isa'diagrammatic ofa dy- Wiew of the voltmeter in the circuit namo or other electric generator.

' E represents blocks of insulating material,

onfwhich are supported the thin rectangular strips of wire F, which latter are supported 1.Wi1' S being secured to the at-points between the insulating-blocks I (Z d, which are arranged in spirals or folds, Y

terminals CC.

011 the upper side. of the high resistancc 1 wires (Z d arelaid thin rectangular strips of mica-F",which are secured in place b qelamps sucli'zvariations- .current and utilizing the latter series of high-resistance E by the supports. E, attached to the base-board. On the mica: strips are disposed the fine platinum or German-silver wire eating apparatus,

the ends of the ing witnesses or bolts f. Small pins g of insulating material are inserted through holes formed in the mica strips and into the supports E and E, and serve to retain the folds of the high-resistance wire against displacement and prevent the folds of the wire from coming in contact with one another. The thermo-spiral is placed on thetop of the mica strip just asinthe ammeterherginbefore described.

Fig. 5 is a diagrammatic view of the improved voltmeter in the'circuit of a dynamo or other electric generatorG, a resistance II being included in the circuit of the machine.

Fig. 6 is an enlarged plan View of theapparatus, the strips orbars 1 being composed of antimony andthe strips or bars 2 of bisinuth; or any other suitable metal may be used. The bars or strips 12 are connected at one end with the electric COHdllCtOIft', and are connected at their oppositeends with a bar a. Theadjacentends of the bars 1 and 2 .are soldered together, or' otherwise con- 'nected. The joints formed between the ends ofbars or strips 1 2, connected with bars a, are known astlie hotjoints, and thejoints connected -with the bar a as the cold joints.

This figure represents one of an alniost innu met-able numberof diiferent constructions of thermo-spirals or thermo-piles that might be employed in carrying my invention into effect; a

Having fully described my invention, what I claim as new, and ,desire to secure by Letters'Patent, is-

. 1. Themethod of indicating the strengthof an electric current ofconstant or varying strength, consisting inconverting .such cur.- rentor a portion of it into a thermo-electric v to operate a current-indicating apparatus, substantially as set forth.

2. The method of indicating the strength of an electric current of constant or conductor by the current or a portion of the current to be measured and transmittingtho heat thus generated to the alternate joints of a thermo-pile or,thermo-spiral,and thereby generating an electric current and uiilizing the latter in actuating a current-imlicating apparatus, substantially as set forth.

3. The method of indicating the strength of an electric current, consisting inhea'tinga conductor by passing through it the current to be measured, or ting the heatso generated directly to thealternate joints of a thermo-pile, and thereby generating a thermoelectric current and util-- -izing t he latter in actuating a current-indisubstantially asset forth.

In testimony whereof I have signedrthis specification in the presence of two subscrib- GUSTAV PFA KUCHE. \Vitnes'ses:

W. AJPALLANT, KDLPOST.

varying strength, consisting in' heating an electric ITO- a portion of it, transmit- 

